Glass-grinding process and apparatus



. 1,635,833 Feb. 1, 1927.] F. GELSTHARP ET AL GLASS GRINDING PROCESS AND APPARATUS Filed Dec. 31, 1924 INVENTORD Patented Fete, l, 1927.

ldl lll l fi STAT Fi l FREDERICK GELSTHARP AND JOSEPH. C. PARKINSON, OF TARENTUM, PENNSYLVANIA,

ASSIGNORS T0 PITTSBURGH PLATE GLASS COMPANY, A CORPORATION OF lPENN- SYLVfaNIA.

GLASS-GRINDING PROCESS AND APPARATUS.

Application filed December 31, 19724. -Serial No. 759,122.

The invention relates to a process and apparatus for grinding glass'sheets in the manufacture of plate glass, and vparticularly to the application and grading of the abrasive employed. The apparatus and process has its principal use in connection with the straight away grinding or surfacing opera; tion, in which the glass sheets to be surfaced are carried upon a train of cars or tables, which are carried slowly beneath a series or grinding machines provided with suitable runners engaging the glass sheets. It is necessary in this operation, to supply the machines with a series of grades of abrasive, ordinarily sand, the machines beneath which the sheets are first passed receiving the coarsest grade of abrasive, and finer and liner grades being supplied, as the sheets progress beneath the succeeding machines and are gradually smoothed. The up paratus and process comprising the present invention have for their objects thc'provision oi an apparatus and process by whose use; (1) a greater economy in the use of abrasive is secured as compared with processes and apparatus heretofore employed, (9.) the abrasive is separated into clean, distinct grades with a minimum admixture of the liner grades with the coarser grades, and "3) a maximum accumulation of the liner grades of abrasive for the liner grinding is secured, which is particularly important, inasmuch as there is a scarcity of the liner grades of abrasive in the processes as heretofore employed. One form of apparatus for practicing the invention is illustrated in the accompanying drawings wherein:

l i 'ure 1 is a partial sideelevation and partial vertical section. And Fig. 2 is a diagrannnatic plan view showing the rele ticn or the grader to the series of grinding machines.

Referring to the general arrangement of the apparatus as indicated in Fig. FLA, B, U, D, etc. are a series of grinding machines arranged in series over a train of cars E mounted on the track F; (l is a grading tank which supplies the series of grinding inachines, or which the ones shown are only a part; and H and I are a pair of surnps from which the grading tank G- is supplied.

The grinding machines may be of any ap proved type, but as illustrated, they coinprise a supporting framework made up of the channels 1, 2, 3, etc., which serve also to support the grading tank G; a grinding runner a; a spindle 5, which carries the runner; an electric motor 6 operating through suitable reducing earing in the casing 7 to drive the spindle, the tubular bearing member 8 in which the spindle is ournalled; the casting 9 secured to the framework; and the arms 1.0 and 11 pivotally supported upon the casting 9 and engaging trunnions carried by the bearing member 8, the arm which supports the weight of the runner and the parts which drive it being counterbah anced by means of the spring 12 carried by the connecting rod 13 and adjustable in tension by means of the nut 14-.

The cars or tables E upon which the glass to be ground is carried ma be of any approved type and are preierahly given a movement of translation along the track F by means of the rack 15 secured tothe bottoms of the cars and driven from the shaft 16 through the intermediary of the spur gears 17 and 18.

Extending along the sides of the series of cars are the drainage troughs 19-19 connected to the pipe 20 which discharges into the sump 21. The used abrasive and Water from the grinding machines are thus collect ed and supplied to the sump for grading and reuse as hereinafter described,

'lhe tank G- is provided with a plurality of outlets 22, 23, 24:, 525, etc, leading from different levels and emptying into troughs 26, 27, 98-, 29, etc. for carrying mixtures of abrasive and water to the various grinding machines A, B, C, 'D, etc. The grader is illustrated as supplying four grinding Inachines, but it willbe understood in practice a grader will ordinarily supply a much largernuniber of machines and that in some cases the same grade will be supplied to several machines, the drawings being merely designed to illustrate the invention in one of its simplest forms.

Mounted at the center of the tank by means of brackets attached to the walls of the tank and not shown is a casing made up of the series of tapering sections 30, 31, 32 and 33, the ends of such sections preferably coining opposite the outlets 532, :23, 24: and Located above the tank is a. de watering cone 35 to which the mixture of used abrasive and water from the sump H ill) is supplied by means of the rotary pump 36 and the ipin 87. The cone has an outlet 38 at its lower end, which discharges into the cup 39. such cup 39 having outlet spout 40 with its extreme lower end turned laterally as indicated at 21. The spout 4O isjournalled in a hearing 4:2 and carries the pulley 43 by means of which it is rotated; by a belt s ieirtending around the driving pulley of a motor-45. A baille piate 34 carried by a pair of straps 46 receives the discharge from the spout 40, and the rotation of suchf spout serves to distribute the mixture of abrasive and water over the tank area below the level of the liquid'thercin. he hearing 42 is preferably carried by means of a transverse platc 47 secured to the Walls of the tank 'G, while the motor is preterably carried upon a bracket rigidly se-- cured to the Wall of such tank.

The overflow from the grading tank (it passes through the pipe -18 leading froiuthe upper end of the tank to the sewer, such overflow serving to carry off any mud or sand which is too fine for use. The excess Water supplied to the (lewatcring cone is Withdrawn through the overflow pipe 49 leading to the sump I. Some very fine sand and mud from the cone is also carried from the pipe 49 to the sump I, but the major portion of this is eliminated from the system by an overflow 50 from such sump leading to the sewer. Similarly, the sump H is pro vided' with an overflow 5L for carrying to the sewer mud and sand which is too fine for use. The water which. collects in the sump I is supplied under p ssure to the bottom of the grading tank (i oy means of the rotary pump 52 and the pipe connection 53. This serves to gire a grading tiovv of Water upward through the tank, so that the diii'erent grades of abrasive in the tank are collected at different levels, the coarsest abrasive being iocated at the bottom and the grades being finer andfiner' at increasing'distahces from the bottom of the tank.

In operation, the cycle of grinding, collecting the used abrasive from the tables, grading it, and re-supplying it to the various machines is conducted in a continuous cycie, the abrasive being used over and over again. and those portions automatically eliminated which become too fine for service. New sand is added to the system from-time to time to take the place of the sand which has become too fine for use, such sand being preferably supplied to the sump H. Additionai water to take the place of that which passes to the sewer through the "overflows i8, 50' and 51 is supplied by the water which is directed onto the tables or cars to wash them after the glass has passed one grind ing runner and preliminary to its passage be heath another one employing; a finer grade of abrasive: The diminution of a portion oi 35 serves to give a thicker mixture in the tank (i, and at the same time this surplus water which is eliminated is not wastethhut' is utilized in giving the upward. grin a ow through the tank by means the pump hi3 heretofore explained. The rotation of the spout i0 assists in distributing the abrasive acrosse larger area of the tanlr. than the case if the spout discharged at one -.-point, which tends to prevent the abrasive from moving rlownwardiy through the tonic due to a massing; or concentration Which would tend to carry the liner abrasives clear to the bottom of the tank or in any event to-tooe level. The use of casings 39 to 33, serres to give much. cleaner g ies of abrasive as Withdrawn from the outlets to then would he the if those casings were not employed, since they serve prevent s lateral movement at we coarser abrasive it moves downward thro i1 the tank in seeking its proper level. With the arrangement as shown, any course abrasive, for instanceavhich belongs belo /vs the level of the casing 33, cannot find its "Way to the outlet 25 since in order to do so, it would have to move upward alongthe path indicated by the arrow in Fig. 1 and there is little chance ofthis occurring asthese perticics of course abrasive of such Weight that they must move downward under the conditions of fiOW in the grader it is adiustcd for service, The arrangement also we a corresponding advantage over those systems in which all. of the abrasive and water are introduced at the bottom of the tank from the sump, since under these condi tions a great deal of the line sand is diverted laterally through the various outlet passages before it reaches its proper level. The present arrangement insuresthat there is no wastage of the fine abrasives, since by no chance can these finer abrasives get to a point below their proper level. This is important since there is u scarcity of the finer abrasives in systems such as those here illustrated, so that they must be conserved for use With the machines which are designed to carry out the finer grinding operations. This is also particularly important in a continuous grinding" operation, as opposed to an intermittent one, such as is conducted with. circular grinding tables, since in. a coutinw ous operation, there is no opportunity to collectthe finer grades while the courlse grinding is being carried. on. is the case in an intermittent operation, so that it is essential that none oi. the liner grades should be allowed to be carried out of the grader with the coarser grades, in which latter connection. they interfere with the coarse grindinrg operations rather than assist them, as is Well known in the art.

insi ers lt will lee-understood that the invention is not limited to the details of construction shown either as to the grading mechanism or as to the grinding machines. Also that the terms tank and sump are used in their broadsense to mean any sort of a receptacle whether located above the ground" shall be outlets at'a plurality of different levels. The form illustrated is preferred because of the fact that the overlapping ends of the sections reduces the tendency of any grades which are too course for use at these levels to escape laterally without also moving upwardly, Which practically prohibits any such improper lateral escape of the coarse abrasive.

' What we claim is: t

1. A process of grading and applying abrasive to a. grinding machine, winch con sists in collecting theused abrasive and Water from the grinding machine, separating a portion of the water from such mixture and causing it to flow upward through a body of water, introducing the remainder of the mixture into-the top of such body and siinult-aneousl Withdrawing a. mixture of water with t e. desired grade of abrasive from said body and supplying it to the grinding machine.

The seg- 2. In combination with a grinding masaid overflow, means for continuously liftin 0' the mixture of Water and'abrasive fromsaid first sump and discharging it to said recep-' tacle, means for supplying the Water from said second sump upwardly to the lower portion of said grading tank to provide a grading flow upwardly therethrough, and' means for withdrawinga mixture of Water and abrasiveof the required grade from the tank and supplying it to the grinding m achine, v

3. In combination with a grinding machine, a sump arranged to receive the mixture of used abrasive and water from said machine, a grading tank, means for separating a portion of the water from said mixture, means for supplying such water to the lower portion of the grading tank under pressure to provide an upward grading flow therethrough, means for supplying the rest of said mixture to the top of the grading tank, and means for Withdrawing a mixture of water and the desired grade of abrasive from the tank and supplying it to said grinding machine.

In testimony whereof,- We have hereunto subscribed our names this 27 day of October,

FREDERICK GELSTHARP. JOSEPH C. PAR-KINSON. 

